I dont mean it smells or needs a cleaning. Im mean as far as bringing some spring and shape back to it. I bought it in 2005 and its a pillow top, so no flipping. I rotate it about 2-3 times per year.
I thought a mattress should last longer than 8 years, but it might just be time to replace it
Unless you've already decided on a new one, look into "mattress surgery", where you'll find the popular way is to cut 3/4 sides around your mattress' top, so that it's a flap you can open & remove all the worn foam, then replace with your own comfort layers of polyurethane and/or memory foam and/or latex etc. I've done it with a couple of mattresses myself, & actually prefer to completely extract the springs instead- ditch not only all the foam on top & bottom & around, but also the entire casing & everything but just the springs, & build from there. Springs must still have some life left, & was a decent mattress, relatively high spring count/heavy gauge etc.
Anyway a new mattress would be nice too. Just try to find out everything about not only the springs + every layer of foam you're paying thousands of dollars for- source & density of memory foams, whether hr/hd polyurethanes, dunlop or talalay latex & percent natural/synthetic, ild's etc. <--(edit)& ideally not one whose layers are all glued together so that you can't shuffle/replace them as they wear, without an electric knife anyway (which gets messY).
After tons of experimentation with all of the above & then some, I've found my back loves nothing better than springs + latex, with as little between myself & the latex as possible. Though no foam will last as long as it would if you protect it with mattress pads/casings etc. (why warranties insist on them). JUst feeeeeeeels better w/o.